The present disclosure relates to additive manufacturing systems for building three-dimensional (3D) items with layer-based, additive manufacturing techniques. In particular, the present disclosure relates to additive manufacturing systems for printing large or elongated 3D items, and methods for printing 3D items in the additive manufacturing systems.
Additive manufacturing systems are used to print or otherwise build 3D items from digital representations of the 3D items (e.g., AMF and STL format files) using one or more additive manufacturing techniques. Examples of commercially available additive manufacturing techniques include extrusion-based techniques, jetting, selective laser sintering, powder/binder jetting, electron-beam melting, and stereolithographic processes. For each of these techniques, the digital representation of the 3D item is initially sliced into multiple horizontal layers. For each sliced layer, one or more tool paths are then generated, which provides instructions for the particular additive manufacturing system to print the given layer.
For example, in an extrusion-based additive manufacturing system, a 3D item may be printed from a digital representation of the 3D item in a layer-by-layer manner by extruding a flowable item material. The item material is extruded through an extrusion tip or nozzle carried by a print head of the system, and is deposited as a sequence of roads on a substrate in an x-y plane while the print head moves along the tool paths. The extruded item material fuses to previously deposited item material, and solidifies upon a drop in temperature. The position of the print head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D item resembling the digital representation.
In fabricating 3D items by depositing layers of an item material, supporting layers or structures are typically built underneath overhanging portions or in cavities of 3D items under construction, which are not supported by the item material itself. A support structure may be built utilizing the same deposition techniques by which the item material is deposited. The host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the 3D item being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the printing process. The support material adheres to the item material during fabrication, and is removable from the completed 3D item when the printing process is complete.